CVE-2026-40355
What it is
In MIT Kerberos 5 (aka krb5) before 1.22.3, there is a NULL pointer dereference if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, causing the process to terminate in parse_nego_message.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 0.6% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.6% in the next 30 days (EPSS).
- Severity: 5.9 MEDIUM (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.6% · EPSS, next 30 days
- Weakness
- CWE-476 · NULL pointer dereference
- Record status
- Modified
Affected
- Mit Kerberos 5 ≤ 1.22.2
Attack profile CVSS 3.1 · 5.9
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-40355.md and follow it. Check whether this project is affected by CVE-2026-40355. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html
- https://github.com/krb5/krb5/commit/2e75f0d9362fb979f5fc92829431a590a130929f
- https://web.mit.edu/kerberos/advisories/
- https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html
References
- https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html
- https://github.com/krb5/krb5/commit/2e75f0d9362fb979f5fc92829431a590a130929f
- https://web.mit.edu/kerberos/advisories/
- https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html